We present the case of a 19-year-old male who suffered from Langerhans cell histiocytosis (LCH) 12 months after having been treated for recurrent Hodgkin's disease (HD). Immunophenotypic characterization and electron microscopic analysis were useful for the exclusion of a bone relapse of Hodgkin's disease or any other differential diagnosis. The association of LCH with HD or other malignancies is rare but more frequent than previously believed. The significance of such an association and the pathophysiology of LCH are still open questions.